A self-doping type electroconductive polymer is usually soluble in water and therefore, can be easily formed into an arbitrary shape or formed into a film, which characteristic enables easy production of large-area film. Moreover, such a polymer also exhibits an extremely excellent formability in electric devices which require microscopic processing and therefore has been widely used these days.
On the other hand, a chemically amplified resist has been an essential material technically common in lithography using light or charged particle radiation such as electron beam or ion beam. However, such a resist is susceptible to use environment and is known as a resist hard to handle. Especially, positive chemically amplified resist is even harder to handle, and it involves a concern over adverse effects by water-soluble coating material.
In a case where the resist is coated with a water-soluble coating material, there has been a problem that acid generated through exposure to light is neutralized by the coating material when the hydrogen ion concentration (hereinafter abbreviated as “pH”) thereof falls in a certain range or that, even without exposure process, acid supplied from the coating material forms the same situation as in the case where the resist is exposed to light. Thus, since a trace amount of acid in the coating material greatly affects sensitivity of the resist, the pH value of the coating material solution is important. Such a problem occurs as film thinning phenomenon in a positive-type resist while it occurs as formation of hardly soluble layer or insoluble layer in a negative-type resist.
As methods for preventing the phenomenons, a method where pH decrease is controlled by using a buffer solution containing a weak acid and an amine (JP-A-H11-189746), a method using a composition containing a fluorinated aliphatic sulfonic acid or a fluorinated aliphatic carboxylic acid(JP-A-2003-29410) and the like have been proposed.
Also, a film of a composition containing a water-soluble electroconductive polymer, a vinyl-base polymer emulsion and a nonionic surfactant which has excellent storage stability has been disclosed (JP-A-H11-185523).
In recent years, under circumstances where resists patterned in accordance with miniaturization of the smallest circuit line width in semiconductor devices tend to easily collapse, attempts to make aspect ratio of resist pattern appropriate are being made in order to prevent the phenomenon and therefore, resist film thickness is with a tendency to be reduced. After a resist pattern has undergone developing process, the pattern is transcribed onto a substrate through dry-etching process.
In this process, the importance of dry-etching resistance of resists is growing, and since changes in resist form attributable to antistatic films have a great influence on pattern printing, the demand for maintaining performances of resists is growing keener and keener.